Modules for monitoring signals, such as power line signals, are well known in the art. Typically, the monitoring module includes an integral display for providing a visual representation of various parameters of the monitored signals. When used to monitor power, the monitor/display unit must be located in close proximity to the power line, thus limiting easy access by an operator needing to read the display. In addition, when reading the display, the operator may be exposed to high voltage potentials associated with the power line.
Monitoring systems including a display located remote from the monitoring module also are known. The display modules in such systems typically are adapted specifically for the associated monitoring module and may include the intelligence or logic necessary to display the various parameters of the monitored signals. Often, a product-specific cable must be used to interconnect the display and monitoring modules. Although this arrangement provides access to the monitored information remote from the monitoring module and permits the display site to be selectively located or moved, the additional circuitry and components increase the cost and complexity of the overall system. Moreover, system flexibility is limited by restricting the display module to use with a particular type of monitoring module. And most remote systems support only a single display module, limiting access to displayed information to a single site. In systems which support multiple display modules, each display module must have a unique address, identifying its location in the system. Address assignment typically is implemented by hardware, such as dip switches, in the display module. Thus, if display modules are used in another system, an operator may need to reset the dip switches.
Accordingly, it would be desirable to provide a communication system for displaying monitored information at locations remote from the monitoring module. The display module preferably would be electrically isolated from high voltage potentials that may be present at the monitoring location. In addition, the communication system would support multiple display modules, thus providing flexibility in display location and the type of information displayed at each location. Each display module could be used interchangeably in any type of communication system and would not require product-specific interconnections, thus enhancing flexibility while controlling costs. The communication system would automatically configure each display module, providing address and display information, as well as automatically reconfigure the display modules upon adding or removing modules from the system, thus dispensing with cumbersome dip switches that must be manually set by an operator.
In a communication system having multiple interconnected modules, however, the probability of a defective interconnection increases. Accordingly, it would be desirable to provide a communication system that also automatically detects and locates communication failures caused by defective interconnections.